This paper examines and compares trends in intergenerational educational mobility in East Asia, West Europe, and North America in the 20^th century. The expansion of educational opportunity is a global phenomenon, but its timing, pace, magnitude, and gender gap differ between countries. We are especially interested in identifying similarities within such differences, which may reflect shared educational values, practices, and institutions that help us better understand educational inequality from a global perspective. Methodologically, it is challenging to compare educational attainment between generations and across cohorts, and even more so to compare the long-term trends in intergenerational educational mobility between countries. Unlike many previous studies that are based on absolute measures of educational attainment and log-linear models that control for changes in the marginal distributions, we take a simpler approach: we measure a person’s educational attainment relative to peers of the same gender with his/her percentile position in the education distribution of a 10-year birth cohort obtained from census microdata. This relative measure enables us to examine long-term trends in intergenerational educational mobility using easy-to-interpret rank-rank regression slope at the parent-child pair level based on census microdata as well as international and national survey data. Moreover, as it accounts for gender-, cohort-, and country-specific educational differences in its essence, it is also a comparable measure for international comparison. So far, with the relative ranks tentatively calculated from the Barrow-Lee educational attainment datasets and individual-level data from International Social Survey Project, East Asian Social Survey, the Survey of Health, Ageing and Retirement in Europe, and several national surveys, our preliminary analysis already produces new findings on regional similarities and gender disparities in the evolution of educational mobility. We are in process attaining census microdata to calculate accurate relative attainment ranks for each country, and incorporating additional survey data for further comparative research.